The record of environmental change in the past fifty years inferred from the geochemistry of reservoir sediments from lake Lokvarsko jezero (Croatia)

A reservoir sediment core was used to investigate the changes in environmental geochemical conditions in the past fifty years in a small (approx. 26 km2) drainage basin in located in the mountainous region of Gorski Kotar. A total of 40 elements and 5 radionuclides were analyzed in every 2 cm of approximately 50 cm of reservoir sediment. Since the construction of the reservoir in 1952 several major events have been registered in the sediments. The peak and termination of barite mining is indicated by concentration trends in S, Ba, Sr, Ag and Cu. The effect of acid rain deposition through viewed through a considerable Na depletion in sediments especially after 1980. Increasing trends are indicated for Cd, Pb, V, Cr, Ni, on the basis of calculated “ cultural enrichment factors” . Preliminary chronostratigraphy with the aid of 137Cs indicates accumulation rates of less than 1cm annually. Elevated trace element concentrations in the sediments accumulated in the past fifteen years show that atmospheric deposition of pollution and acid rain deposition is still altering the geochemistry of this region.